Stoker



Feb. 3,1942. R. L. BEERS STOKER Filed Nov. 27, 193% 3 Sheeis-Sheet l am I - N I N 5 z 0 To j INVENTOR.

BY ROYCE L.BEEfi$ ATTORNEYS Feb. 3, 1942. BEERS 2,271,967

STOKER Filed Nov. 27, 19:59 s Sheets-Sheet 2 I INVENTOR. ROYCE LLBEIERS ay 4%:

ATTORNEYS Feb. 3, 1942. R. L. BEERS 2,271,967

STOKER Filed No v. 27, 1939 3 Sheets-Sheet 3 INVENTOR. ROYCE L.BEERS Wm WM ATTORNEYS Patented Feb. 3, i942 STOKER Royce L. Beers, Birmingham, Mich., assignor to Detroit Stoker Company, Monroe, Mich., a. corporation of Michigan Application November 27, 1939, Serial No. 306,406 a 12 Claims.

The invention relates to stokers of that type including a sprinkler type fuel feeding mechanism and a forwardly traveling horizontal grate upon which the fuel is deposited. The invention relates more particularly to various features of the construction including: first, the means for supporting and cooling the fuel feeding mechanism and for simultaneously supplying over-fire air to the furnace; second, in the peculiar construction of the traveling chain grate; third, in

the means for taking up slack due to wear and stretch in the chain; fourth, in the construction of an adjustable air seal for regulating the distribution of airthrough the grate; fifth, in the means for avoiding the jamming of ash and clinker between the ends of the traveling grate bars and the side walls of the furnace; and, sixth, in various other novel features of construction as hereinafter set forth.

In the drawings:

Figure 1 is a vertical longitudinal section through the structure;

Figure 2 is a cross section therethrough;

Figures -3 and 4 are enlarged cross sections through one of the grate bars, respectively on line 33 and line 4-4 of Figure 2;

Figure 5 is a horizontal section on line 55 of Figure 2;

Figure 6 is a perspective view showing a modified construction; 1

Figure 7 is an enlarged side elevation showing the means for retaining the grate bars in engagement with each other while passing around the forward sprocket;

Figure 8 is a plan view thereof;

Figure 9 is an enlarged cross section of a portion shown in Figure 2.

With stokers of the type above referred to, the fuel is fed from a hopper at the front of the furnace to a rotary impeller which hurls it into the furnace chamber over the grate. The grate is of the endless chain type and travels forward from the bridge wall to a point located beneath the fuel feeding mechanism where it discharges the ash into a pit before returning to the rear. Such construction necessitates a substantially fiat arch support for the fuel feeding mechanism 1 providing clearance for the grate and the ash carried forward thereon. It is also necessary to protect this supportfrom the heat of the furnace, as well as to cool the fuel feeding mechanism. This I have accomplished by the following construction.

Combined supporting and cooling means for fuel feeding mechanism construction of this sprinkling mechanism is not a part of the present invention, I have omitted illustrating the same. D is a fuel receiving hopper above the casing C from which fuel is delivered to the sprinkler. E is the traveling grate on which the fuel is. deposited, which extends from the bridge wall F forward into a chamber C beneath the fuel feeding mechanism and in rear of the lower portion H of the furnace front.

As above stated, clearance must be provided between the grate E and the fuel feeding mechanism together with its supporting means. For this purpose I employ a hollow beam or girder I which extends transversely between the side walls of the furnace over the chamber C. As specifically shown, this hollow girder comprises an I-beam I having its web in a vertical plane, a channel beam I with its web in a horizontal plane and its forward flange welded or otherwise secured to the web of the beam I, and a channel beam I having its web in a vertical plane and welded or otherwise secured to the rear flange of the channel beam 1 There is also a top plate I secured to the top flange of the beam 1' and extending rearward therefrom being connected at its rear endto a member I supported on the beam I and constituting a portion of the furnace front. This member I has an air channel I formed therein which leads to a hollow apron I at the bottom of the fuel opening B. A .damper I controls the opening into the channel I to regulate the amount of air entering therein. The plate I is also provided with an opening I communicating with the fuel feeder and distributing cooling air thereto.

The construction just described constitutes a hollow box girder supported at its opposite ends on the side walls of the furnace and connected with means for propelling air thereinto. Such means may, however, be of any suitable construction and is not illustrated. However, during operation of the stoker cool air is supplied in sufficient quantity to not only protect the girder I, but also to cool the fuel feeding mechanism and to supply over-fire air through ports in the apron I". This girder not only supports the fuel feed mechanism, but also the upper portion of the front wall of the furnace, while a lining C of refractory material is suspended from the girder and constitutes the top of the chamber C.

Traveling grate propelling chains F. The bars E are attached to the chain by pins F extending through the lugs E and E and also constituting the pivotal connection between adjacent chain links. To permit of easily detaching the bars from the chain the pin F is provided at one end with an enlarged head portion F engaging a corresponding aperture in the lug E This aperture has an entrance slot E which is of a width equal to the diameter of the body portion of the pin F so that by driving said pin out of engagement with the lug E and with its small end flush with the side of the chain, the head F will be removed from the aperture permitting lateral disengagement of the bar. In other words, the pin is disengaged from the lug E while the slot E in the lug E permits the latter to be withdrawn over the pin, this bein accomplished without disengaging the chain links from each other. Normally the pins F are locked from disengagement by a cotter pin F extending through a transverse aperture therein adjacent to the lug E.

The upper portion of the chain grate on which fuel is deposited is supported by rails G extending longitudinally thereof and overlapped by the opposite end portions of the bars E. These rails in turn are supported on a frame which as specifically shown includes the longitudinally extending I-beams G, the channel beam G beneath the side I-beams, the transverse channel beams G and G and other elements as hereinafter described. The whole forms a closed chamber beneath the grate into which air under pressure is fed, so a to pass upward through apertures E in the grate bars and to support combustion of the fuel deposited thereon. Proper distribution of the air to the grate bars is accomplished by a series of transversely extending V-shaped partitions G having adjustable dampers G located at the apices thereof. The adjacent grate bars E also form air pockets between the depending flanges E thereof from which pockets the air passes directly into the apertures E". There is also a segmental flange E projecting laterally from a flange E and upon which a portion E of an adjacent bar rests, thereby substantially sealing the pocket and directing all of the air therein into the apertures E The construction is, however, such as to permit a swinging of the bars E about the pivot pins F at a certain point in the travel of the chain grate, thereby forming openings between adjacent bars for the passage of air and for the discharge of ash.

Slack compensating means Chain grates in use have a tendency to elongate due to stretch in the links and wear in the pivotal connections. To compensate for this certain constructions heretofore used have provided for the adjustment of One of the sprocket shafts in relation to the other. With my improved construction I dispense with this adjustment and provide other means for taking up slack. This comprises supporting rails for the under or return portion of the chain grate, which are adjustable in height and inclination. Thus, while these rails partially support the return portion of the chain to relieve stresses due to weight of the bars, they may be adjusted downward to take up any slack between individual links. As specifically shown, stationary rails H are arranged at an inclination beneath the forward part of the return portion of the chain grate, and adjustable rails H pivoted at H are arranged beneath the rear portion thereof. Links H each having a threaded portion engaged by nuts H on opposite sides of 'an apertured bearing H serve as a means for lowering the rails H and changing the inclination thereof.

Air sealing means As has been stated, the air chamber beneath the grate is partially enclosed by the beams G and G on opposite sides of the furnace, together with the rails G and the grate bars E slidably supported thereon. To complete the enclosure, there is arranged at the inner end of the grate a transverse channel beam G upon which is supported a segmental casing (3 extending around the portion of a chain grate in engagement with the sprockets F These members abut against the bridge wall of the furnace, which extends upward beyond the same. At the juncture between this bridge wall and the segmental casing 6*, there is arranged a series a tuyere members J having an inclined front face overlapping and extending upward from the grate bars E. The tuyere members are detachably supported on the member G being attached thereto by depending hooks J engaging a rib G Air is supplied to the interior of the tuyre members through channels G between the portion of the grate engaging the sprockets F and the member G The tuyeres J serve to prevent the piling up of unconsumed fuel adjacent to the bridge wall and to a height greater than the bed supported on the grate.

At the opposite or forward end of the grate the enclosure of the air chamber is completed by the following elements. G is a beam for supporting the forward end of the inclined rails H. G is a parallelly arranged beam spaced from the beam 6, and G is a casing member supported on these beams arranged beneath and fitting against the portion of the chain grate returning from the sprocket F to the rail H. Between the upper and returnportions of the chain grate and in rear of the sprocket F is a transversely extending channel beam G which extends upward from the channel beam G These beams support bracket bearings G in which the shaft F is journaled. Similar bracket bearings support the shaft F from the beam G. G is an apron connected to the beam G and extending downward into contact with a plate C; which rests upon the inverted flanges E of the bars E in the return portion of the chain grate.

Sliding air seal The construction above described completes the enclosure of the air chamber with the exception of the seal between the beam G and the underside of the grate bars in the forwardly traveling portion of the grate. It will be understood that the fuel which has been deposited on the grate is gradually consumed during its forward movement, combustion being supported by the air from the chamber passing through the ports E The consumption of the fuel must be completed before the grate bars E pass around the sprocket F for at this point any unconsumed portion will be dumped with the ash. I, therefore, find it desirable to regulate the amount of air that passes upward through the grate bars which is accomplished by means of a sliding seal. This comprises a plate K extending transversely across the air chamber in contact with the shelf K, which extends rearward from the beam G. The plate K has at its rear end a shoe member K which b'eafsagainst the depending flanges E of the bars E to form sealing contact therewith. K are links connecting the plate K to rock arms K on a rockshaft K which latter extends across the furnace and through an aperture in the beam G An adjustable rock arm K outside of the beam G serves as a means for rocking the shaft K thereby moving the plate K rearward or forward with respect to the shelf K. Thus, the shoe K will be adjusted in position to form a variable cut-off for the air passing from the chamber through the ports E of the grate bars.

The width of the stoker may correspond either to the length of a single grate bar E or any desired multiple thereof, the adjacent sections being supported by the rails G. At the outer sides adjacent to the side walls of the furnace there is a tendency for ash and clinker to accumulate and by wedging between the walls and the grate bars will interfere with the operation of the latter. Such result I have prevented by the use of ledge plates L which are mounted on the outer rails G to extend from a point adjacent to the ends of the grate bars to the side wall of the furnace ll hese plates have horizontal portions L and depending inclined flange portions L which latter bear against the rail G at the point close to the end of the bars E. The ledge plates L are further provided with lugs L forming supporting bearings on the rails G and recessed to receive the heads of bolts L which secure said plates to said rails. With this construction only a narrow space is left between the flanges L and the ends of the grate bars so that ashrand clinker will not be forced between the bars and the rails.

Controlling means for pivoted grate bars As has been described, the grate bars E are pivotally attached to each other and to the chain links by means of the pins F so that each bar is capable of swinging about its pivot. It is necessary, however, to prevent this swginging movement during the forward travel of the bars and while said bars pass around the sprockets F at the forward end of the stoker. As the ends of the bars'E' in the forwardly traveling portion of the grate slidably engage the rails G, and as the axes of the pivot pins are below the top surface of said rails, there will be no tendency for the bars to swing about their pivots during such forward movement. On the other hand, when the bars E disengage from the forward ends of the rails G and travel around the sprockets, F, there would be a tendency for them to fall outward. This I have prevented by means of shoes M and M, which extend around concentric with the axis of the shaft F and overlap the ends of the bars E. These shoes may be secured by any suitable means, but preferably by bolting them to segmental flanges M extending radially outward from the cap members M for the bearing brackets G The flangesM have T-shaped slots M therein with which the heads of the bolts M may be engaged, said bolts passing outward through apertures in overlapping portions M and M" of the shoe members M and M to be engaged by clamping nuts M Such shoes will hold thebars E from swinging outward during the period while they are traveling downward around the sprockets F and into engagement with a member G The rails H and H will also hold the bars E from swinging outward on their pivots until a position is reached beneath the sprocket wheels F Here the bars are released and will be actuated by gravity to turn about the pivot pins F into positions where they are separated from each other and will dump any remaining ash adhering thereto. The separation of the bars also opens air passages which connect the portion of the air chamber below the return portion of the chain grate with the air space above the same.

In Figure 6, I have shown a modified construction for detachably securing the grate bars E to the chains F. In this construction the pin N for connecting the chain links is of uniform diameter throughout its length and provided with cotter pins for engaging transverse apertures N near the opposite ends of the pin. The lugs on the grate barswhich embrace the chain links are both provided with apertures N of greater diameter than the pin N and with entrance slots N equal in width to the diameter of the pin. Members N sleeved upon the pin N are externally of a size to flt into the apertures N with extension portions N which flt in the slots N Thus to attach the grate bars to the pins N the lugs are first engaged with said pins through the entrance slots N and when concentrically arranged themembers Ntmay be moved axially on the pin into engagement with the apertures N and slots N The cotter pins will then hold these parts in such relation until such t:' 16 as it is desired to remove a grate bar.

' What I claim as my invention is:

1. In a stoker a traveling grate comprising a series of transversely extending adjacent overlapping perforated grate bars spaced rails on which the opposite end portions of said bars are slidably supported and a chain to which the forward edge portions of said bars are pivotally connected, saidpivotal connections being in a plane parallel to and below the top of said rails whereby the forward draft of said chain will tend to hold the overlapping portions of said bars in substantially sealing contact with each other and also hold the opposite end portions of said bars in contact with said rails to restrict the air feed to the perforations of said bars.

2. In a stoker, a traveling grate comprising a 5 series of transversely extending perforated grate bars with the rear edge portion of each bar overlapping and forming a substantially sealing contact with the forward edge portion of a succeeding bar spaced rails on which the opposite end portions of said bars are slidably supported, an endless chain having its upper forwardly traveling portion arranged in a plane parallel to and below the top of said rails, forward and rear sprockets around which said chain passes, and pivotal connections between the forward edge portions of each bar, and said chain, whereby during the forward movement of said chain said bars will be held in sealing contact with each other and said rails to restrict the air feed to the perforations in said bars, said pivotal connections permitting the rotation of said bars to separate the same during the return movement of said chain.

3. In a stoker a traveling grate comprising a propeller chain, a series of adjacent grate bars extending transversely of said chain, each bar having a perforated top portion, a deep flange depending from the forward edge of said top portion, a pivotal connection between said flange and said chain, and a ledge on said flange forming a substantially sealing seat for the rear edge portion of the top of an adjacent bar to substantially prevent passage of air therebetweeri, whereby the flanges of succeeding bars will form therebetween an air pocket in communication with the perforations through said top portion.

4. In a stoker a traveling grate comprising a propeller chain sprockets around which said chain passes a series of adjacent grate bars extending transversely of said chain each having a perforated top portion, a deep flange depending from the forward edge of said top portion, a pivotal connection between said flange and said chain permitting rotation of said bar relative to the chain, and a segmental ledge on said flange concentric to the axis of said pivotal connection forming a seat for the rear edge portion of the top of an adjacent bar, said ledge permitting the relative movement of adjacent bars without separation of the same while passing downward around the sprocket and a shoe for limiting rotation of said bars on their pivotal connections while traveling around said sprocket said pivotal connection permitting the rotation of said bars to separate the same during the return movement of said chain.

5. In a stoker, a traveling grate comprising a chain, a pin forming a pivotal connection between adjacent links of said chain and projecting beyond the same, said pin having portions of different diameters, a grate bar, a lug on said bar apertured to pivotally engage the large diameter portion of said pin, said aperture having an entrance slot for the passage of the small diameter portion of said pin.

6. In a stoker, a traveling grate comprising a chain, a pin forming a pivotal connection between adjacent links of said chain having a portion of larger diameter projecting beyond said chain, a grate bar, a pair of lugs on said grate bare embracing said chain, one of said lugs having an aperture for pivotal engagement with the large diameter portion of said pin, said aperture having an entrance slot for the passage of the small diameter portion of the pin, whereby said bar may be attached or detached by an axial movement of said pin.

7. In a stoker, a traveling grate comprising a chain, a pin forming a pivotal connection between adjacent links of said chain and projecting beyond the same, a grate bar, 2. lug on said grate bar having an aperture of larger diameter than said pin and an entrance slot to said aperture for the passage of said pin thereinto, and a member on said pin fitting said aperture and engageab-le therewith by a movement axially of said pin to detaohably lock said grate bar to said chain.

8. In a stoker, a traveling grate comprising a chain, a pin forming a pivotal connection between adjacent links of said chain and projecting beyond the same, a grate bar. a lug on said grate bar having an aperture of larger diameter than said pin and an entrance slot to said aperture for the passage of said pin thereinto, and a bushing slidable on said pin into engagement with said aperture to detachably lock said grate bar o said chain.

9. In a stoker, a traveling grate comprising a propeller chain, a sprocket around which said chain passes, a series of adjacent grate bars extending transversely of said chain each bar having a perforated top portion, a deep flange depending from the forward edge of said top portion, a pivotal connection between said flange and said chain, and a segmental ledge on said flange concentric to the axis of said pivotal connection forming a substantially sealing seat for the rear edge portion of the next forward bar and permitting a relative angular movement of th same about the axis of said pivotal connection, and means for limiting the relative angular movement of adjacent bars to prevent separation of the rear edge portion of one bar from said segmental ledge of the adjacent bar during the passage of said chain about said sprocket.

10. In a stoker, a traveling grate comprising a propeller chain, a sprocket around which said chain passes, a series of adjacent grate bars extending transversely of said chain each bar having a perforated top portion, a deep flange depending from the forward edge of said top portion, a pivotal connection between said flange and said chain, and a segmental ledge on said flange concentric to the axis of said pivotal connection forming a substantially sealing seat for the rear edge portion of the next forward bar and permitting a relative angular movement of the same about theaxis of said pivotal connection, and a shoe for limiting the relative rotation of adjacent bars to prevent separation of the rear edge portion of one bar from said segmental ledge of the adjacent bar while passing about said sprocket.

11. In a stokcr, a traveling grate comprising a series of longitudinally extending spaced supporting rails, a plurality of separate parallel chain gratesmach consisting of comparatively short grate bars extending transversely between a pair of rails with their opposite end portions overlapping and supported upon said rails in sliding and substantially sealing contact therewith, and chains to which the opposite end portions of said bars are connected the bars of each of the separate chain grates being disconnected from and independent of those of the adjacent parallel chain grate;

12. In a stoker, a traveling grate comprising a series of longitudinally extending spaced supporting rails, a plurality of parallel chain grates each consisting of perforated comparatively short grate bars extending transversely between a pair of rails with their opposite end portions overlapping and supported upon said rails in sliding contact therewith, chains to which said bars are connected, a segmental ledge on each bar concentric with the axis of the chain pivot and forming a substant ally sealing seat for the rear edge portion of the next forward bar whereby the air fed through said grate is restricted to the perforations of said bars.

ROYCE L. BEERS. 

